We identified physicochemical, volatile compound, and microbial community differences between three grades of roasted-sesame-like flavored Daqu. The Daqu grades had different physicochemical characteristics. The concentrations and proportions of various esters reflected sensory evaluations of the Daqu classes but no rule linking the flavor compound types and concentrations to Daqu grade was identified. The prokaryotic microorganism communities were similar in premium-and first-grade Daqu but very different in general-grade Daqu. The eukaryotic microorganism communities in premium-and general-grade Daqu were similar, but the genus abundances were more similar in the premium-and first-grade Daqu samples than in premium-and general-grade Daqu. ARTICLE HISTORY

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Fermented food is loved by people all over the world because of the unique flavor. Esters of short-chain fatty acids are renowned for their contribution to the flavor of different fermented foods. In these foods, esters are produced in a diverse proportion because of microbial activities. 1,2 It is often needed to add esters as flavor additives to maintain and enhance the flavor or add a special flavor tone. 3 The growing demand for specific flavor has been a major scientific research area to produce esters on a large scale and in a safe and cost-proficient way. Natural sources such as fruits are the primary origin of esters. Esters can be extracted from these natural sources using various techniques such as fractional distillation, compound extraction using supercritical fluids, continuous liquid-liquid extraction, pervaporation, and adsorption. 4,5 Plants contain esters in a very low amount and also depend on the plant growth and climatic conditions. 6 Therefore, direct extraction of esters from natural sources is costly, time-consuming, and lower in yield, and the quality is not up to the mark. 7-9 But the extracted esters are marked as natural and can be used for food production. 10